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The role of special gases in etching

The etching gases (special gases) of silicon wafer are mainly fluoron-based gases, including carbon tetrafluoride, carbon tetrafluoride/oxygen, sulfur hexafluoride, ethane hexafluoride/oxygen, nitrogen trifluoride, etc. However, due to its isotropy and poor selectivity, the modified etching gas usually includes chlorine-based (Cl2) and bromo-based (Br2, HBr) gases. The reaction products include silicon tetrafluoride, tetrachlorosilane and SiBr4. Chlorine-based gases, such as CCl4, Cl2, and BCl3, are commonly used for etching aluminum and metal composite layers. Products mainly include AlCl3 and so on.

Etching is the chemical and physical process of selectively removing unwanted material from the surface of a silicon wafer. The purpose of the etching is to reproduce the mask pattern correctly on the glued silicon chip. Etching is divided into wet etching and dry etching. Wet etching is etching by chemical reaction with liquid chemical reagent or solution. Dry etching USES the ions or free radicals in the plasma generated by low voltage discharge to react with the material, or achieve the purpose of etching by physical action such as bombardment. The main medium is gas. The advantages of dry etching are obvious anisotropy (that is, the vertical etching rate is much higher than the transverse rate), good feature size control, low chemical use and treatment cost, high etching rate, good uniformity and high yield. The commonly used dry etching is plasma etching.

Etch gas industry term, etch is the substrate on the surface of the processing without photoresist mask such as silicon oxide film, metal film etch away, so that the photoresist mask area to preserve, so that the substrate surface to get the required imaging graphics. The basic requirements of etching are that the edges of the graphics are neat, the lines are clear, and the transformation of the graphics is small. There are wet chemical etching and dry chemical etching. The gas used in dry etching is called etching gas, usually fluoride gas, such as carbon tetrafluoride, nitrogen trifluoride, hexafluoroethane, perfluoropropane, trifluoromethane, etc. Due to the strong direction of etching, accurate process control, convenient, no degluing phenomenon, no substrate damage and contamination, so its application is increasingly extensive.

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